This invention relates to substantially pure, isolated populations of monocytes and dendritic cells, methods of obtaining such purified cell populations, the use of such purified cells for immune and cancer therapy, transplant rejection and T-cell suppression or anergy (immunotolerance), the preparation of vaccines against immune diseases and cancer, the activation of dendritic cells by, for instance, ligation with a CD58 fusion protein, and for stimulating the production of IL-12 in vivo without the systemic use of a cytokine.
Dendritic cells are antigen-presenting cells found in all tissues and organs, including the blood. Specifically, dendritic cells present antigens for T lymphocytes, i.e., they process and present antigens, and stimulate responses from naive and memory T cells. In addition to their role in antigen presentation, dendritic cells directly communicate with non-lymph tissue and survey non-lymph tissue for an injury signal (e.g., ischemia, infection, or inflammation) or tumor growth. Once signaled, dendritic cells initiate the immune response by releasing IL-1, TNFα, and various other inflammatory cytokines which trigger lymphocytes and myeloid cells. Various immunodeficiencies, e.g., towards tumors, are thought to result from the loss of dendritic cell function.
Monocytes may also be involved in T-cell suppression and autoimmune diseases. These cells may play a role in blocking transplant rejection by suppressing T-cell and B-cell activation, thus preventing T-cell or antibody cytopathetic effects.
Accordingly, it would be desirable to obtain substantially pure populations of non-cytokine treated monocytes and dendritic cells in order to exploit the role of these cells in immunotherapy, cancer therapy and T-cell suppression. The isolation of these cells is difficult, however, due to the low frequency of occurrence of the cells in the circulating white cell population of the mammal, and because of the lack of a surface marker expressed by fresh and cultured dendritic cells to distinguish them from monocytes.
Conventional methods for cell isolation which enrich subpopulations of cell mixtures include, e.g. density gradient separation, fluorescence activated cell sorting, immunological cell separation techniques such as panning, complement lysis, resetting, magnetic cell separation techniques, and nylon wool separation. Different patterns of expression of cell surface antigens have been used in some cases to identify different cell types. Certain disadvantages of many of these reported methods are that they can be time-consuming, labor-intensive, costly, require large amounts of reagent, result in low specificity, low sensitivity, contaminated mixtures, poor and/or inaccurate separation, and the loss of desired cells. Certain other methods, such as the treatment of the cell population with cytokines, can change the properties, functions, or viability of the desired cells. Thus, prior methods generally are inefficient, time-consuming, expensive, and do not optimize for pure populations.
Commonly assigned U.S. Pat. No. 6,194,204 discloses that although both dendritic cells and monocytes express roughly the same levels of CD14, CD-2 is an effective marker for dendritic cells and can be used to separate dendritic cells and monocytes in mixed cell populations. This patent also discloses that a vaccine for treating cancer can be prepared from dendritic cells which express CD 14, preferably treated with or induced to express cancer-specific antigen to stimulate host cell immunity to the cancer upon administration.
Accordingly, it is an objective of this invention to provided substantially pure, isolated populations of dendritic cells and monocytes, and methods for preparing such substantially pure populations.
It is another objective of this invention to provide vaccines for use against a wide variety of diseases, such as cancer or AIDS, and to provide therapeutic formulations for the suppression of T-cell activity for the treatment of autoimmune disease or in the treatment of organ transplant rejection.
It is a further objective to treat a mammal having cancer or an immune disease, or to treat a mammal to prevent organ or tissue rejection.
It is a still further objective of this invention to provide a method for stimulating IL-12 activity in vivo in a mammal at targeted tissues and organs.
It is an additional objective of this invention to provide therapies for the treatment of autoimmune diseases.